CLASSIFICATION BASED ON CATALYTIC REACTION

Enzymes are grouped into six major classes on the basis of the
types of reactions they catalyze.

1. Oxidoreductase
2. Transferase
3. Hydrolase
4. Lyase
5. Isomerase
6. Ligase

It is an enzyme that catalyzes an oxidation-reduction reaction.

Oxidoreductase

Oxidation of a substrate

Oxidases

Reduction of a substrate

Reductases

Introduction of double bond (oxidation) by formal
removal of two H atoms from a substrate, the H
being accepted by a coenzyme

Dehydrogenases

It is an enzyme that catalyzes the transfer of a functional group from one
molecule to another.

Transferase

Transfer of an amino group between substrates

Transaminases

Transfer of a phosphate group between substrates

Kinases

It is an enzyme that catalyzes a hydrolysis reaction in which the addition of a
water molecule to a bond causes the bond to break.

Hydrolase

Hydrolysis of ester linkages in lipids

Lipases

Hydrolysis of amide linkages in proteins

Proteases

Hydrolysis of sugar-phosphate ester bonds in
nucleic acids

Nucleases

Hydrolysis of glycosidic bonds in carbohydrates

Carbohydrases

Hydrolysis of phosphate-ester bonds

Phosphatases

It is an enzyme that catalyzes the addition of a group to a double bond or the removal of a
group to form a double bond in a manner that does not involve hydrolysis or oxidation.

Lyase

Removal of H2O from a substrate

Dehydratases

Removal of CO2 from a substrate

Decarboxylases

Removal of NH3 from a substrate

Deaminases

Addition of H2O to a substrate

Hydratases

It is an enzyme that catalyzes the isomerization (rearrangement of atoms) of
a substrate in a reaction, converting it into a molecule isomeric with itself.

Isomerase

Conversion of D isomer to L isomer, or vice
versa

Racemases

Transfer of a functional group from one position
to another in the same molecule

Mutases

It is an enzyme that catalyzes the bonding together of two molecules into one
with the participation of ATP.

Ligase

Formation of new bond between two substrates,
with participation of ATP

Synthetases

Formation of new bond between a substrate and
CO2, with participation of ATP

Carboxylases